Method of spinning rayon



Nov. 10, 1936.

E. R. MCKEE El AL METHOD OF SPINNING RAYON Filed Aug. 19, 1933 '2 Sheets-Sheet l .14; MM 5. A5155,

BY 6. WJMa/LA,

ATTORNEY Nov. 10, 1936.

E. M KEE ET AL METHOD OF SPINNING RAYON Filed Aug. 19, 1933 2 Sheets-Sheet 2 ATTORNEY Patented Nov. 10, 1936 METHOD OF SPINNING RAYON Edward R. McKee, Buffalo, and Archibald *8. Hunter, Kenmore, N. Y., assignors to Du Pont Rayon Company, New York,

- tion of Delaware N. Y., a corpora- Application August 19, 1933, Serial No. 685,816

3 Claims.

This invention relates to the manufacture of artificial threads, filaments, straw or the like. More particularly, it relates to the. manufacture by the bucket spinning process of materials of the type mentioned, having substantially uniform affinity for dyestuffs and preferably also being substantially uniform in denier.

One of the common and well-known methods of producing artificial viscose silk is the bucket spinning process. According to this process, a constant predetermined quantity of a viscose solution is spun through a spinneret into a spinning bath and drawn therethrough for the desired bath travel by a constant speed drawing wheel. The thread is then withdrawn from the bath and collected in a bucket rotating at a constant R. P. M,

to form a cross-wound cake.

The cakes of yarn produced by the method just described may be purified and dried as cakes, or washed and then reeled into skeins for further purification, or reeled into skeins directly from the acid cake and then purified.

The yarn of the ultimate bucket cake and, more particularly, the yarn fully processed as cakes, exhibits a non-uniformity in dyeing and denier. In general, the dyeing becomes markedly deeper and the denier becomes'noticeably heavier from the outside to the inside of the cake. This degree of difference varies with the denier and filament size of the yarn spun and is more pronounced with yarn of heavier denier and filament size.

We have found that by increasing the thread speed within the spinning cycle and by simultane-' ously increasing the viscose delivery,. we are able to obtain athread which, after washing, purifying and drying, not only dyes uniformly gut also possesses a denier which is far more uniform than that of yarn produced heretofore by the bucket process.

It is, therefore, an object of this inventionto provide a method of producingartificial thread by the bucket process which dyes uniformly even with direct dyes and, preferably also, has a denier more uniform than yarn produced by the bucket process prior to this invention.

Another object of this invention is to provide a method of producing artificial filaments, threads, straw or the like having a substantially uniform amnity for dyestufls even with direct dyes, and preferably. being of uniform denier, which comprises increasing the quantity of cellulosic solution delivered to the spinneret and increasing the thread speed within the spinning cycle, with or without increasing the speed of rotation of the bucket in which the thread is collected.

Other objects will appear from the following description, appended claims, and accompanying drawings illustrating an exemplification of means for increasing the speed of the feed or draw-oil wheel and means for increasing the pump delivery and wherein:

Figure 1 is a diagrammatic side elevation, partly in section, of a spinning machine;

Figure 2 is a plan view of the drive for the feed wheel;

Figure 3 is an end elevation of the drive shown in Figure 2;

Figure 4 shows an arrangement for producing a variable speed viscose pump drive;

Figure 5 illustrates an end elevation of the drive mechanism illustrated in Figure 4'; and

Figure 6 is an end view of the spinning machine showing the arrangement of the units upon said machine.

In accordance with the principles of the instant invention, a viscose solution is delivered to a spinneret and extruded therefrom into a spinning bath through which the thread is drawn for the necessary distance. The thread is then withdrawn from the spinning bath by the feed wheel or draw-off roller and is then conducted into a rotating bucket, where the thread is wound into the formof a cake.

To secure the desired results, the thread speed and the viscose delivery are simultaneously increased during the spinning cycle. If desired, the other parts of the apparatus, such as a traverse bar and the bucket, may also be increased in speed during the spinning cycle.

v The increasing thread speed is accomplished by increasing the peripheral speed of the draw-off roller. When the draw-off roller is cylindrical in shape, the increase in speed may be secured by a variable speed transmission connected to the drive of said wheel. Alternatively, the speed of the thread may be increased by utilizing a tapered or irustro-conicalwheel. In such an arrange-. ment, the thread, during the spinning cycle, is progressively advanced on the tapered surface toward the end of the wheel which has the larger diameter.

In place of a single feed wheel. double feed wheels may be employed and the amount of stretch of the thread between the wheels varied, such as by increasing the peripheral speed of both wheels, and generally that of the second wheel. When double feed wheels are employed,

the first of such wheels may be located in the The viscose delivery is changed by supplying increased quantities of viscose to the spinneret. This is secured by causing the viscose pumps to deliver increasing quantities of viscose to the spinneret during the spinning cycle, for instance, by increasing the rate of rotation of the pump shaft.

The thread speed and the viscose delivery may be changed during the spinning cycle at the same rate or at different rates. These changes are progressive and may be uniform or non-uniform, continuous or intermittent. In the preferred form of the invention, the feed wheel speed is increased, so that at the end of the spin the thread draw-off speed is in the neighborhood of 2%-20% faster than at the beginning of the spin, depending, to a large extent, upon the treatment of the final yarn, size of the individual filaments, denier, etc. The pump delivery is increased during the spinning cycle 0.50 to 1.0 times the percentage increase of the feed wheel speed.

In order to more clearly explain the nature of the invention, several specific illustrative examples are given. It is to be understood that the invention is not restricted to these precise examples.

Example I.-Increasing feed wheel speeds and pump deliveries at dz'fierent rates From cellulose, such as is commonly used in the viscose rayon industry, there is prepared a viscose solution having a viscosity of about 4,000 centipoises, a cellulose content of 7%, and a caustic soda content of 6%. This viscose is ripened to an index of 4 (Reinthaler and Rowe, Artificial Silk", 1928, page 69), and is spun through a spinneret having 40 openings, under conditions below noted, to form a thread having an ultimate denier of 150. The viscose is extruded into a coagulating bath heated to 45 C. and having the following composition by weight.

Percent Sulphuric acid 9 Sodium sulphate 19 Glucose 4 Zinc sulphate 0.7 Water 67.3

The freshly formed thread is delivered by a feed wheel into a normal size bucket, i. e. about 7 inches in diameter and 4 inches deep, revolving at 7,700 B. P. M. The thread travelin the bath is constant throughout the spin at 16 inches, and a tension of approximately 16 grams is applied to the thread by means of a rotating guide, such as described in United States application, Serial No. 419,806. At the beginning of the spin, the pump delivery is 14.3 grams of viscose per minute, and the feed wheel has a peripheral speed of 2,830 inches per minute. The pump delivery is increased throughout the spin at a uniform rate until at the end of 6 hours, the end of the spin, the delivery is equal to 14.9 grams per minute.- Likewise, the feed wheel speed is increased at a uniform rate until at the end of 6 hours, the end of the spin, the peripheral speed of the feed wheel is equal to 3,040 inches per minute.

The cake is dotted from the bucket, wrapped in cheese-10th, such as disclosed in United States Patent No. 1,688,702, washed with soft water by the usual drip method for 12 hours, desulphured with a solution containing 0.3 sodium carbonate at -90 C. by allowing the solution to drip over the cake for 5 hours, again washed with water for 5 hours, and finally bleached by sprayformly can be Cake spun without Compencom nsated cake sat on Outside denier 144. 3 150. 1 Inside denier-.. 148. 2 149. 8 Diflerence 3. 9 0. 3

Example II-Increasing feed wheel speeds and pump deliveries at the same rate The viscose, coagulating bath, spinning set-up, spinning time and purifying process are the same as in the preceding example, and the thread spun has an ultimate denier of 150. The peripheral speed of the feed wheel at the beginning of the spin is 2,800 inches per minute, and, under these conditions, the pumps are set to deliver 13.7 grams of viscose per minute. The speed of the feed wheel shaft and the pump shaft are gradually and uniformly increased in the same proportional amounts until, at the end of the spin, they are running 8.5% faster than at the start of the spin.

The finished yarn so produced dyes uniformly, but physical tests show that the denier difference within the cake is not reduced.

In some cases it is not considered necessary to compensate for denier so long as the denier difference between the inside and outside of the cake is not unreasonable, and, in such cases, the method just described provides a simple, cheap and easily operative way of securing this end.

Example III.-Accele1'ating the speedo! the entire machine Another way of producing yarn that dyes unisecured by accelerating the speed of the entire machine during the spinning cycle. One manner by which this can be accomplished is by changing the frequency of the generator supplying the electric current to the spinning machine to increase the speed of the whole machine, including buckets, feed wheels, pumps and traverse bar, so that the thread speed is increased 7.5% throughout the spinning cycle. The spinning conditions and the purification process are as specified in the first example, with a thread draw-oil! speed at the start of 2,830 inches per minute and a pump setting to produce denier yarn. Yarn that dyes uniformly is thus produced.

In the preceding examples, the yarn is completoly processed in cake form. When it is desired to purify the yarn in the form of skeins, it

5 hours, contrifuged to rebecomes necessary to vary the thread speed and pump delivery somewhat differently, because 1am in skeins is normally free to shrink during processing and drying, whereas yarn in the form of a.

- cake is prevented from uniformly shrinking.

Example IV.Cake desulphuring and skein bleaching Cakes of yarn are spun as described in Example II, except that the pump delivery and feed wheel speed are uniformly increased about 4.2%

throughout the spin, that is, the viscose pumps are set to deliver 14.3 grams of viscose per minme at the start of the spin, at which time the feed wheels are turning at a peripheral speed of 2,918 inches per minute, and at the end of the spin the pumps are delivering 14.9 grams of visknown to the art, and'then washed and dried.

Skeins of yarn from all parts of the cake would dye uniformly.

Example V.-- -Sk ein desulphuring and bleaching Cakes'of yarn are spun under conditions as set forth in; Example'IV,-except that the bucket speed 'is 6,000 R. P; M. rather than 7,700 R. P. M., and

the peripheral speed of the feed wheel and 'the pump delivery are proportionally less than 2,467

. ods.

inches per minute at the start and 11.7 gramsof viscoseper minute, respectively. The spinning cycle is the same, i. e. 6 hours, and both feed wheel speed and the pump delivery are gradually and uniformly increased during this time about 4.1%.

The acid cakes are dofied from the' buckets', washed by the drip method until acid free, and

then dried. The dried cakes arereeled into skeins' and then purified, i. e. desulphured and bleached, in this form in accordance with well-known meth- The yarn from all these, skeins dyes uniformly according to the test set forth hereinafter. I

, Under some conditions of spinning and processing, it may be found that the correction desired cannot be obtained by a constant rate of increase of the feed wheel and pump, in which case, by increasing their speeds at variable rates, optimum results can be obtained. For example, when spinning into very large buckets to form large thick cakes by continuously spinning over a long period of time, such'as 12 hours or more, it will in gen-- eral be found advantageous to increase the rate of spinning non-uniformly and, preferably, ac-

cording to a smooth curve.

It may be desirable, also, because of mechanical simplicity, to increase the speeds stepwise, such as 4, 5, 6, 7 or more or less times, throughout the spinning cycle. The manner and amount of variation can most easily be determined experi-.

mentally for each method of producing yarn.

In the course of experimentation, it has been found that a uniform denier yarn is produced when the pump delivery alone is gradually decreased 4% during the spin. If it-is desired to compensate for tenacity or elongation in order that these properties may be uniform throughout the yarn mass, the principle outlined herein need only be applied.

It is not essential to theinstant invention that all the details above given be thus, although, if conditions are appreciably changed, it will then become necessary to change compensating con ditions. cosity and the degree of ripeness of the'viscose, the composition of thecoagulating bath, the. length of travel of the thread in the bath, the

. initial speed at which the threadis spun, and

many other factors, either in the spinning or in the processing of thethread formed. It is es- For instance, we may change the vissential only that compensating factors be properly selected according tospecific conditions.

Further, the rotating bath guide may be replaced by a plurality of guides or'one or more stationary-guides of any description. The guide may even be eliminated entirely and the thread spun directly from the spinneret to the feed wheel. In place of a single feed wheel, double feed wheels may be employed whereby the amount of stretch is varied between the wheels by increasing the speed of both rollers, but generally that of the second roller at a higher rate. Or, thefirst of two positively driven rollers maybe located in the bath, in which case it will function as a bath guide.

There are a number. of mechanical combinations which will produce thedesired changes in speed which normally will be selected to suit the specific case. We have found that combinations shown diagrammatically in the accompanying drawings are satisfactory.

A spinning machine, as'shown in Figure 1, is provided with duplicate mechanisms on both sides thereof. For convenience and brevity, one side thereof will be described.

Referring now to Figure 1, the reference numere al I designates generallya pump, feeding the viscosesolution supplied thereto by means (not shown) to a spinneret 2, from which the-viscose is extruded in the bath 3. The quantity of vis,-

cose delivered to the spinneret by the pump l is generally controlled by means of a shaft 4 which operates thepump .mechanism as is well known in the art. The freshly formed thread 5 is drawn by means of the feedwheel 6 through the bath 3 for the required distance, where it may coop crate with guides, tension-imposing means, etc.

The feed wheel 6, which draws the thread through the bath'3, also withdraws it therefrom and directs it into the rotating bucket I, where it is collected. The feed wheel 6 is mounted on one end ofa shaft 8, the opposite end of which is provided with a gear 9'which is driven through a gear l0 mounted on the main shaft II, which is connected. to the output shaft l2, of a variable speed transmission l3, such as the P. I. V. drive of theLink-Belt- Company (see also their catalog book No. 1274).

Referring now to Figures 2 and 3, the reference numeral l3 designates a gear driven from an external source (not shown) and connected by gears 14 and It to a constant speed shaft l6 of the variable speed transmission unit IS. A sprocket I! on the constant speed shaft l6 of the variable speed .transmission unit l3 drives through the chain I8 and sprocket IS, the speed reducers-20 and 2|. A gear rack 22 connects the gear 2 I' to the gear 23, which is fixed to the shaft that controls the setting of the variable speed transmission unit l3 and thus controls the speed of the shaft II. In operation, the clutch 25 is released, permitting the speed control gear 23 to be set at the initial point by drawing the rack 22 back by the handle 24. The clutch is then re-engaged and'the spinning begun. The gear trains substantially the pound portion of the same four cakes.

4- H, I8, 20, 2| and 23 are also selected so as to give the desired rate of change of speed.

Referring now to Figures 4 and 5, there is disclosed a device for changing the speed of the pump shaft, whereby the amount of the viscose delivered to the spinneret is changed. The mechanism for changing the viscose delivery is same as that used for increasing the speed of the feed wheels, and described in connection with Figures 2 and 3. Referring again to Figures 4 and 5, the pump shaft 4 is driven through gears 26 and 21, the latter being driven by an output shaft 28 of the variable speed transmission 29. The constant speed shaft 30 of the variable transmission unit 29 is driven by gear 3|, which is driven through gears 32, 33, 34,-and 35, the latter gear being driven from an external source (not shown). A sprocket 31, secured to the constant speed shaft 30 of the transmission unit 29 by means of a sprocket chain 38, and a sprocket wheel 39 drive the speed reducer 40 and the gear 41. A gear rack 42 having a handle 43 connects the gears 4| and 44, the latter being fixed to the shaft for controlling the setting of the variable speed transmission unit and thus controlling, in conjunction with the gears 26 and 21, the speed of the shaft 4. A clutch 45, similar to clutch 25, is provided for making the desired adjustment bythe rack 42. The operation is the same as the device illustrated in Figures 2 and 3.

The arrangement of the units is shown diagrammatically in Figure 6.

It is well known that by careful selection of the yarn, that is, from certain portions of spun cakes, or by manipulating the dyeing procedure, or -by carefully selecting the dyes used, or by making a construction which will minimize dyeing variations, those skilled in the art can minimze natural irregularities in the dyeing properties of rayon. On the contrary, in the sense of this invention, a uniformly dyeing yarn is represented by the composite yarn of a number of spun cakes, the'extremities of which, when dyed in the form of the construction with the dye and under the dyeing conditions specified herebelow, show no difference in dyeing to a degree objectionable to those trained in the art. The type of construction specified herein is recognized by those skilled in the art as a procedure having a minimum tendency to obscure dyeing variations.

We specify, therefore, the use of an eight-end Wildman tubing. Four adjacent ends of the tubing shall be from and include the extreme outside 0.10 pound portion of four cakes containing at least 0.50 pounds of yarn. The other four ends shall be from and include the extreme inside 0.10

This construction is known to the trade as a 4/4 Wildman.

The tubing shall be boiled off (90-100 C.) for 35 minutes in a solution containing, per gallon of water, 0.3 ounce trisodium phosphate, 0.25 ounce olive oil soap, and .05 ounce sulphonated castor oil, such as is commonly sold under the trade name monopole oil. The ratio between the goods and the bath shall be 1 to 30. After thorough rinsing, the tubing shall be dyed to a full shade with Pontamine Sky Blue GBX (color index No. 518). The goods shall be entered at a temperature of about 100 F. and the temperature of aoeopov the bath raised to the boiling point in 30 minutes. After rinsing, the tubing shall be whizzed and dried in the usual manner.

It should be understood that the uniformity of dyeing claimed for the yarn made by the method herein described is not limited to the use of Pontamine Sky Blue 6BX and to the procedure indicated above. Experience has shown that a yarn which dyes uniformly under the above exacting conditions will dye uniformly 'under all practical procedures encountered in the trade.

The chief advantage of our invention is that it enables us to produce a yarn which can be dyed uniformly. This is a property which has long been sought by the artificial silk industry and, because of non-uniform yarn prepared according to the prior art has cost the manufacturer and converter an enormous amount of trouble. Not only is our invention capable of obliterating this sore spot in the industry, but at the same time it permits the production ofeven denier thread which likewise is very desirable.

Since it is obvious that various changes and modifications may be made in the above description without departing from the nature or spirit thereof, this invention is not restricted thereto except as set forth in the appended claims.

We claim:

1. A method of preparing artificial threads or the like having a substantially improved uniform affinity for dyestuffs by the bucket process which comprises effecting compensation for variations which would otherwise cause non-uniformity in the dyeing quality of the yarn only by increasing the rate of delivery of the thread to the spinning bucket and simultaneously increasing the pump delivery to the spinneret in an amount suflicient to produce a yarn of substantially uniform denier.

2. A method of producing artificial threads or the likehaving a substantially improved affinity for dyestufis which comprises spinning a cellulosic solution into a spinning bath, drawing the thread from the spinneret by a driven wheel, passing the thread around a second driven wheel having a higher peripheral speed than the first wheel whereby the thread is stretched, progressively increasing the peripheral speed of the second wheel relative to the peripheral speed of the first wheel whereby the thread is stretched and delivered to a rotating bucket at an increasing rate, progressively increasing the pump speed sufficient to produce a yarn of substantially uniform denier and collecting the yarn in a rotatin bucket.

3. A method of preparing artificial threads, filaments, straw or the like having a substantially improved uniform affinity for dyestuffs which comprises spinning a cellulosic solution into a spinning bath, withdrawing the thread or the like from said bath, and delivering it to a rotating bucket at a progressively increasing rate until the thread speed is from 2% to 20% faster at the end' of the spinning cycle than at the beginning thereof, progressively increasing the pump delivery to the spinneret during the spinning cycle 0.5 to 1.0 times the percentage increase of the thread dyeing properties, the

speed and subsequently purifying and drying the thread.

EDWARD R. McKEE. ARCHIBALD S. HUNTER. 

